different core types (foam pvc, divinicell vs balsa)

[Nordic cat]

Originally Posted by Alex Pereira

Hi,

I am not a sailor (yet), but i'm involved with core materials and FRP.
Do you know about a new natural core material with a outstanding behaviour in water ??

Agglomerated cork sheets, specially designed for FRP called NL-10, produced by Amorim.
It is being used in Europe (France and Portugal) with good results.

Everybody knows the sealing properties of the wine corks, so the agglomerated cork sheets used has a core material, keep the same properties.

Think about it., a complementary core material.

Do you have link to a site?

Regards

Alan

[Alex Pereira]

Yes,
please go to Amorim Industrial Solutions: Your Challenge, Our CorkRubber Solution! or www.amorim.com

Rgds,
Alex

[Nordic cat]

Alex,

Couldn't find any marine applications????

The stuff we use to build boats with weighs from 80 to 130 kg/m3 (foam or balsa) The cork weights are from 212 kg/m3 and up!!

Maybe I'm looking at the wrong stuff, as the structural strength is also questionable for boat building applications.

Do you have any references we can see in the marine industry?

Regards

Alan

[Alex Pereira]

Sorry, our web site is not updated.

This is a new agglomerated cork developed specially for the Composite process (is on the market since the beggining of the year).

The density is of 120 kg/m3 and the structural strength is good/acceptable.
Also, the absorption of resin is lower than foam (open cell) and Balsa.
Beside that, the cork is very stable till 200 ºC, allowing high curing temperatures.

Not mentioning that is a naturally renewable resource (not like Balsa - we do not cut the trees).

Regards,
Alex

[BigCat]

Originally Posted by Nordic cat

Alex,

Couldn't find any marine applications????

The stuff we use to build boats with weighs from 80 to 130 kg/m3 (foam or balsa) The cork weights are from 212 kg/m3 and up!!

Maybe I'm looking at the wrong stuff, as the structural strength is also questionable for boat building applications.

Do you have any references we can see in the marine industry?

Regards

Alan

Hi, Alan -Yes, I think it's not strong enough, either. Amorim Industrial Solutions: Products - Acoustic Core Materials

Balsa is much stronger than the figures shown at:
http://www.atlcomposites.com/pdf/cores_baltek_SB50.pdf

[mikereed100]

Looks heavy. I would think that compression and shear strength would be inferior to balsa/foam/honeycomb as well.

[Alex Pereira]

Dear all,

What part of new do you do not understand ??

Sorry, for this, but it is a new agglomerated cork, different from the one you can find anywhere. It was be developed to be used has core material in composite.
We are making test in aeronautics and space applications.

Also who can anybody say that is not strong enough ??
On our web site there is no information about this special cork agglomerate.
Probably, was on cork stoppers for wine tests ???

My company belongs to the Amorim Group, world leader in cork products, and we know that in this market there are a lot of big companies, but we have a product that speaks for itself....


Regards

[44'cruisingcat]

Originally Posted by Alex Pereira

Sorry, our web site is not updated.

This is a new agglomerated cork developed specially for the Composite process (is on the market since the beggining of the year).

The density is of 120 kg/m3 and the structural strength is good/acceptable.
Also, the absorption of resin is lower than foam (open cell) and Balsa.
Beside that, the cork is very stable till 200 ºC, allowing high curing temperatures.

Not mentioning that is a naturally renewable resource (not like Balsa - we do not cut the trees).

Regards,
Alex

120 kg/m3 is on the heavy end for cores. So it will need to have similar or better sheer and compression strength to balsa, to attract multihull builders. Unless it is much cheaper of course.

[Alex Pereira]

And what about:
- the easy integration on the process;
- the lower resin absorption;
- the high temperature resistance;
- the very low water absorption;
- the good impact behaviour;
- the excellent low temperature behaviour, and finally
- the fact that is a natural material, naturally renewable (we do not cut the trees to take out the cork, we need the trees growing ....)

all this characteristics aren't important ?

The simple property comparation is good to keep the monopolies (that had defined the properties) ......

We must think out-of-the-box to get innovative and inteligent products.

[Nordic cat]

Hi Alex,

It would be great if you could post the properties we have discussed above. You are right that using renewable resources is/will be a factor in promoting products, and that this requirement needs to be part of the compromise evaluation.

What we don't know are the facts for this new material, I'm sure there have been extensive tests done to evaluate the product, and tweak it, so let's have a look at it.

As an aside, I see Balsa as a renewable resource, as all the main suppliers have plantations, so it's not virgin forest that is being cut down so we can build composite structures. But Balsa also has some characteristics that are not optimal for certain applications.

Regards

Alan

[waikikin]

Alex, sounds/reads interesting, looks like you've got some great products. It would be nice to see some comparitive test results for composite panels say like an impact damage tolerance set of results side by side with balsa, foam & cork so we can see what happens when its bashed up on samples of similar specs for weight/cost/stiffness etc, & might make it easier to represent the material properties to all. Regards & all the best from Jeff.

[fastcat435]

Originally Posted by schoonerdog

over they years I've talked to various people (insurance agents, brokers, lots of builders) about the types of cores used in multihulls and was wondering the groups opinion.

Basically it came down to this, balsa is easier to work with and cheaper, so a lot of boat builders choose it to keep down costs. But on the negative, it's significantly heavier and can have much greater water penetration through the core and more difficult to repair. A boat insurance rep mentioned that insurers look at very negatively at balsa cored boats because of their tendency to have water penetration rot the core for a far greater area than one would assume given the relatively small void that might have been the cause.

The synthetics are more water resistant and lighter, but more expensive, so typically boat builders which are interested in keeping weight down and also making the boat have a more serviceable life. I've used it as a bench mark (one of many) on the quality of a catamarans construction.

Typically the cheaper boats use balsa and the more expensive use synthetic, though there are exceptions.

Any opinions? Any reason to think that Balsa would have merits above the synthetic foams? I'll put in one, from underwood (general manager of broad blue and prout), he believed that synthetics were more prone for offgasing and therefore hull delamination. I found it difficult to believe though since PDQ had been using sythetics since the late 80s with none of theirs have offgasing problems, and I'd personally seen a broadblue 380 being injected with resin throughout the hulls to counter delamination.

When Balsa is infused the resin absorbtion is almost triple as much as with closed cell foam so unless somebody wants to produce a very heavy boat it is a no go item
With the exact same laminate of 1200 grams glass 20 mm foam or balsa 300 glass and 400 kevlar the weight for the foam laminate came out at 5.9 kilo per squire meter and the balsa version at 10.2 kilo or a added weight for our FastCat 455 of 1660 kilo.
A bit much for our taste.

Greetings

[Hud3]

Note: I've moved several threads to an off-forum area for review by the mod team.

[Kai Nui]

To follow Hud's comment, this is a very hot topic for many of you. We encourage thoughtful debate, backed by facts, or personal opinions. We will not, however, allow personal attacks, name calling, or general rudeness. Feel free to continue to debate the accuracy of the information as you see fit, however, should this thread turn to personal attacks again, it will be closed, and infractions given to the offending members.

[Nordic cat]

Originally Posted by fastcat435

When Balsa is infused the resin absorbtion is almost triple as much as with closed cell foam so unless somebody wants to produce a very heavy boat it is a no go item
With the exact same laminate of 1200 grams glass 20 mm foam or balsa 300 glass and 400 kevlar the weight for the foam laminate came out at 5.9 kilo per squire meter and the balsa version at 10.2 kilo or a added weight for our FastCat 455 of 1660 kilo.
A bit much for our taste.

Greetings

I find these figures for Balsa a bit high to say the least.

Take a look at the specifications below for composite panels from ATL.

25 mm of 80 kg/m3 foam with 600 g/m2 each side and 66% fibre weighs 4.0 kg/m2.

19 mm balsa of 150 kg/m3 (the heavy stuff) with the same fibres weighs in at 6.0 kg/m3. This is also much stronger than the 25 mm foam composite, that is why I chose a thinner balsa than the foam.

Using the better Balsa of say 120 kg/m3 would get the weight difference down to around 35% heavier.

Your statement says around 100% heavier.

Your figures for foam seem right, so what did you do with the balsa layup?

There are lots of nice lightweight cats in Balsa core, see the Barocka thread

Regards

Alan